Tuning apparatus



March 30, 1937. D. B. KEIM TUNING APPARATUS 3 Sheets-Sheet 1 [NI/EN To/a: Dmwldflff TTOB/VEK Filed March 30, 1935 IIHIIIIIIIIIIIIHM March 30, 1937. D, B, KEIM 2,075,396

TUNING APPARATUS Filed March 30, 1955 3 Sheets-Sheet 2 WITNESSES. I INVENTOIQ: Q f llolm/lwfijfeum MTTOBNEK Marbh 30, 1937. D. B. KEIM 2,075,396

TUNING APPARATUS Filed March 30, 1935 5 Sheets-Sheet 5 QiTTOB/VEW patented Mar. 30, 1937 UNITED STATES PATENT OFFICE TUNING APPARATUS ware Application March 30, 1935, Serial No. 13,839

4 Claims.

My invention relates to improvements in tuning apparatus for radio receivers and the like.

For the purpose of tuning over a wide frequency range in radio reception, it has been proposed to employ a different set of inductors for use, respectively, in the tuned circuits for each band. Band selection is obtained by operation of suitable switching means for connecting the different sets of inductors in the tuned circuits, selectively.

One of the objects of my invention is to provide tuning apparatus of the general character referred to in which the different connections for band selection can be obtained conveniently by operation of a single control on the front panel r of the apparatus, and in which the respective parts are arranged in a compact manner and are supported against shifting movement with respect to each other underconditions such as might occur aboard ship due to rolling of the vessel.

Another object of my invention is to provide improved tuning apparatus of the character referred to in which the various connections for band selection are made through switch contacts which provide for substantially direct connection 0 between the various coils, for the different bands,

and the condenser and tube assembly comprising the tuned circuits.

Another object of my invention is to provide improved tuning apparatus of the character referred to which has advantages over such apparatus proposed heretofore in the way of increased selectivity and stability.

Other advantages and objects will hereinafter appear.

, In accordance with my invention, a radio frequency tuner employs eight bands to cover the range from 1,000 to 30,000 k. c., a different set of inductors being used in the tuned circuits for each band. The inductors or coils are permanently mounted upon the receiver chassis, while the tuning capacitor and tube assembly are mounted in a movable carriage to make contact with any desired set of coils. The carriage is mounted for sliding movement between groups of the coils, and band selection is obtained by operation of a single control on the front panel of the apparatus to cause sliding movement of the carriage.

My invention resides in the improved construction of the character hereinafter described and claimed.

' For the purpose of illustrating my invention, an

embodiment thereof is shown in the drawings,

5 wherein Figure 1 is a side elevational view of tuning apparatus constructed and operating in accordance with my invention, some of the parts being removed for the sake of clearness; I

Fig. 2 is an end elevational view, looking toward the left in Fig. 1, some of the parts being removed'or broken away;

Fig. 3 is an enlarged, detail, sectional view, the section being taken on the line 3--3 in Fig. 2;

Fig. 4 is an enlarged, detail, sectional view, the section being taken onthe line 44 in Fig. 2;

Fig. 5 is an enlarged, detail, sectional view, the section being taken on the line 5-5 in Fig. 2; and

Fig. 6 is a front elevational view of the apparatus, taken looking toward the right in Fig. 1.

With reference to Figs. 1 and 2, the supporting structure for the tuning apparatus is shown as comprising top and bottom frames in and I2 and side frames l4 and I6 connected thereto to form a rigid structure. Four sets of coils I8, 20, 22 and 24, for as many different bands, are supported in an upright position on the frame l0 and are provided with contacts 26 for making connections thereto. 7

Four sets of coils 28 30, 32 and 34 are supported by the lower frame l2 and extend vertically downward therefrom. These coils are provided respectively with contacts 36 for connecting the same in circuit, as will hereinafter appear.

A carriage, designated generally by the reference numeral 38, carries the capacitor and tube assembly for the tuned circuits, and is supported for sliding movement, in a straight line, between the upper and lower groups of coils, For this purpose, the lower frame I2 is provided with parallel tracks 40 which take the entire weight of the carriage which can slide along the tracks on parallel shoes 42. The tracks 40 are provided with flanges 44' directed inwardly, in opposite directions to' each other, and the shoes 42 are provided with complementary, parallel flanges 46 which interlock with the flanges 44, as shown, to hold the carriage against displacement in any direction perpendicular to the flanges. In this way, displacement or lateral shifting of the carriage, such as might otherwise occur aboard ship due to rolling of the vessel, is prevented.

As is more clearly shown in Fig. 4, the carriage 38 is provided on its upper face with contacts 48 complementary, respectively, to the contacts depending from the upper frame for connecting the coils of the upper group in circuit with the condenser and tube assembly carried by the carriage. The carriage is provided also in its bottom face with contacts 50 similar to the contacts Q8 and which are complementary, respectively, to the contacts extending upwardly from the lower frame :2 for connecting the coils of the lower group in circuit.

The disposition of the various contacts is such that as the carriage 38 is caused to slide along the tracks lil to different positions, one set of the eight sets of coils is connected with the tuned circuits. In this connection, the sets of coils in the upper group are staggered with respect to the sets of coils in the lower group in the sense that as the carriage is moved, the sets of coils in the two groups are connected in circuit alternately. For example, when the carriage is in its extreme lefthand position as viewed in Fig. l, the set of coils 28 is connected in circuit. As the carriage is moved to the right, the set of coils i8 is connected in circuit next, then the set of coils 3D, and then, in succession, the sets of coils 28, 32, 22, 34 and 24, respectively. In this way, the maximum travel of the carriage, required to tune to the eight diiferent bands, is reduced to a minimum. Each one of the eight sets of coils is used for a different one of the eight bands covering the entire operating range, as will be well understood.

For the purpose of causing sliding movement of the carriage 38, a threaded shaft 52 extends through a nut 54 fixed in the front plate 55 of the carriage. The shaft 52 extends through a front panel 58 secured to the stationary frame structure, and is provided with a hand wheel or crank 66 for rotating this shaft. As more clearly shown in Fig. 3, the end of the shaft 52 is reduced and extends through a bushing 62 fixed in a plate 85- secured to the front panel, and a collar 66 is fixed on the reduced end of the shaft. In this way, the shaft is held against axial movement.

For the purpose of indicating to the operator the band to which the apparatus is tuned, a dial G8 is driven from the shaft through a conventional planetary gear designated generally by the reference numeral 78. The outside face of the dial is provided with a scale viewed through an opening 12 in the front panel and which shows to the operator the particular band to which the apparatus is tuned in the operating position thereof at the time.

The gang condenser 14 is adjusted upon rotation of a knob 16 fixed on the end of a shaft 18 which extends through the front panel of the apparatus and through a worm 80 meshing with a worm wheel 82 fixed on the condenser shaft. The worm 8B is journaled in bearings 84 extending upwardly from the bottom of the carriage 38, and is held against axial movement by collars 86 and 88 fixed on the ends of the worm, as shown in Fig. 5. The collar 88 is provided with a V-shape lug 99 which has a sliding fit in a V-shape groove 92 in the shaft 18 and which extends longitudinally of the same. By reason of this construction, the worm 80 is connected for rotation with the shaft 18 and can slide along the latter as the carriage 38 is moved.

"By means of a similar connection, a variable capacitor 94 carried by the carriage, and which might be used for antenna compensation, is adjusted by rotating a knob 96 fixed on the end of a shaft 98. In this case, however, the shaft 98 is square and has a sliding fit in a square hole in a gear illll carried by the carriage 38 and supported for rotation, but held against axial movement. The gear I meshes with a similar gear Hi2 fixed on the shaft of the capacitor 94.

For the purpose of making ground connections where desired, and providing for shielding between the contacts, it is proposed to provide the carriage 38 with contacts I04 arranged to receive and slide along complementary grounding and shielding strips I06 connected to the stationary frames l0 and I2.

The carriage 38 is provided with suitable shielding partitions N18 for preventing reaction between the difierent circuits. Also, the various coils are enclosed by shielding cans, as shown.

From the foregoing, it will be seen that I have provided improved tuning apparatus adapted particularly for radio reception, and in which different sets of coils are used for as many different bands to cover the entire operating range, band selection being obtained by operation of a single control on the front panel of the apparatus. It will further be seen that by reason of my improved construction and arrangement of the various parts with respect to each other, the entire apparatus is relatively compact, and band selechas been disclosed, it will be understood that various modifications are possible without departing from the spirit of my invention or the scope of the claims.

I claim as my invention:

1. Tuning apparatus comprising two groups of tuning elements supported in spaced relation, a carriage supported for sliding movement between said groups, tuning elements common with respect to the elements of said groups and supported on said carriage for movement therewith, said elements being provided respectively with contacts disposed to connect the elements on said carriage in circuit alternately and selectively with the elements of said groups upon sliding movement of said carriage, and means for causing such movement of said carriage.

2. In a radio receiver, a frame, groups of coils supported on said frame, a carriage supported for sliding movement with respect to said frame, tuning means comprising a variable condenser supported on said carriage for movement therewith, said coils and said condenser being provided respectively with contacts disposed to connect said condenser in circuit selectively with said coils upon sliding movement of said carriage to different positions with respect to said frame, means for adjusting said condenser comprising a rotatable member fixed against sliding movement with said carriage and means carried by said carriage and providing an operating connection between said member and said condenser, and means for causing sliding movement of said carriage to said positions.

3. In a radio receiver, supporting frame structure, sets of coils each provided at an end thereof with contacts for making connection thereto, said sets of coils being supported by said structure in two groups spaced from each other and with the contact-ends of the coils in the two groups directed toward each other, a carriage supported for sliding movement between said groups of coils, tuning means supported on said carriage and movable therewith, said carriage being provided with contacts complementary respectively to the coil contacts and engageable with the latter upon sliding movement of said carriage to different positions to connect the coils in circuit with said tuning means, the coil contacts being disposed to connect the coil sets in circuit selectively with said tuning means upon movement of said carriage to the respective operating positions thereof, means for adjusting said tuning means, and means for causing sliding movement of said carriage.

4. In a radio receiver, supporting frame structure provided with a front panel, tuning elements in the form of coils provided with contacts and supported by said structure, a carriage supported for sliding movement with respect to said structure, tuning means supported on said carriage and movable therewith, said carriage being provided with contacts complementary respectively to the coil contacts and engageable with the latter upon sliding movement of said carriage to diiferent positions to connect the coils in circuit with said tuning means, the coil contacts being disposed to connect sets of the coils in circuit selectively with said tuning means upon movement of said carriage to the respective operating positions thereof, means for adjusting said tuning means and extending through said panel for manual actuation thereof, and means for causing sliding movement of said carriage and extending through said panel for manual manipulation thereof.

DONALD B. KEIM. 

